1. Field of the Invention
This invention relates to an electronic camera for recording still pictures on a record bearing medium.
2. Description of the Prior Art
Electronic cameras for recording still pictures by synchronous recording on magnetic disks of small size have been proposed. For this kind of electronic cameras, there have been provided a wide variety of shutter control methods, any of which is to initiate accumulation of photo signals in synchronism with a reference signal, for example, a synchronizing signal representing a phase of rotation of a magnetic disk. As such prior art mention may be made of Japanese Laid-Open Patent Application No. SHO 58-117776 corresponding to U.S. Pat. No. 4,541,016 issued on Sep. 10, 1985. By such prior art methods, however, the time interval from the moment at which the release button has been pushed down to produce a trigger signal to the moment at which the image sensor really starts to accumulate was allowed to vary at random. Because this variation amounted up to 1/60 sec. (33 milliseconds) as the time lag, there was a problem when in application to sports photography, documentary photography, or other like photography where it is of great importance to take good timing for shots.
Another type of electronic camera in which as soon as the trigger signal is produced by the release button, the image pickup element is cleared and starts to accumulate photo signals has also been proposed in U.S. Pat. Application Ser. No. 452,500 filed Dec. 13, 1982 now U.S. Pat. No. 4,599,657. In such an electronic camera, the signals on the image pickup signal are then read out in order to be recorded on a recording medium while being moved by a servo drive based on a reference signal. As the timing for reading out and recording, a timing synchronized with when the aforesaid servo drive is locked is selected.
Such an electronic camera has a large advantage under the aim of minimizing the time lag from the production of the trigger signal of the release button to the start of recording. Yet there was left much more room for improvements.
That is, the time lag until the servo drive is locked cannot be maintained constant, differing from time to time. In case when such a time lag becomes long, noise, for example, due to the dark current is added to the signal obtained by the image pickup element so that video signals of high quality cannot be obtained. In this respect, room for improvements was left.